In the packaging industry, it is often necessary to load two or more items into a container, typically a carton or box. These items may or may not be rigid or have rigid exteriors. For example, a cereal box may need to be loaded with a pair of sealed plastic bags of cereal.
A typical technique for putting a single item into a container, consists of transferring an item from an item supply conveyor or other item supply device into a holder, such as a bucket. This bucket, once loaded is moved along a predetermined path on a conveyor to a container loading station. At the container loading station a container loading machine such as a pusher arm, will load the item from the bucket into the container.
When only a single item is to be loaded into a container, the method is relatively straightforward. Problems are encountered, however, when it is desired to load more than one item into a single container. Loading of multiple items into a container can take place either sequentially or simultaneously, but particularly when the item is flexible, the latter approach is preferred.
With sequential loading, a single item is loaded into each of a series of buckets, and then the container is loaded with items from successive buckets. A container is loaded with one item from a first bucket by means of a container loading machine. A second item is then loaded into the container (which is already partially filled with the first item) from a subsequent bucket on the conveyor. Difficulty in loading the second item into the container is encountered due to physical interaction between the two items.
To try to overcome problems associated with sequential loading of the container with items from successive buckets, the packaging industry began loading two items into a single bucket. The two items are then loaded simultaneously into the container. This method reduces the amount of problematic physical interaction between the two items when loading the items into a container.
One way of simultaneous loading of a container includes having a hesitating bucket at the bucket loading station. The bucket conveyor is designed to permit hesitation of the bucket at the bucket loading area. While remaining stationary, a single bucket is loaded with two items, each item being sequentially loaded into a bucket at the bucket loading station. Due to a finite amount of hesitation that can be incorporated into a continuous conveyor system, an overly long delay or a problem with feeding the second item into the bucket, may result in the bucket leaving the loading station with only a partially filled bucket. This causes problems at the container loading station.
Two other solutions for simultaneous container loading are: (1) the index loader; and (2) the walking beam/robot arm loader.
An index loader requires three conveyors: (i) an item loading conveyor; (ii) an index bucket conveyor; and (iii) a primary bucket conveyor. The index conveyor and the primary bucket conveyor are oriented parallel to each other. The first item may be loaded, via a first item loading conveyor, by being moved onto a "bomb-bay". This first item drops into a bucket on the index conveyor when the bomb-bay is opened. The bomb-bay closes and the next item is then loaded onto the bomb-bay. The bomb-bay opens and the second item is dropped onto the first item. The bucket on the index conveyor remains at the station until it has received the requisite number of items (e.g. two). At this point, the index conveyor is then indexed one position forward thereby providing an empty bucket to repeat the first process. At a later station along the index conveyor, the items in the bucket are simultaneously loaded into a loader bucket moving on the primary, continuous bucket conveyor which has a hesitation feature. A drawback of this type of loader is that an additional, index bucket conveyor (compared with the single item loader) is required for multi-item loading functionality. Moreover, existing single item, sequential loading systems are not easily nor cost effectively retrofitted to add this functionality.
The walking beam/robot arm loader consists of a horizontal arm which has two separate suction type devices, one located at each end. The walking beam is positioned above, and is substantially aligned in the longitudinal direction with, a bucket conveyor. In its first position, one suction device of the arm is located directly above a loading platform. A first item is transported to a loading platform by an item supply conveyor. The bucket conveyor is positioned at an oblique angle relative to the item supply conveyor. The second suction device of the arm is located further downstream in relation to the bucket conveyor. The first suction device grips the item and the arm is moved in a direction upstream, relative to the bucket conveyor's direction of travel, to a point where the first suction device (with an item) is located directly above an empty bucket and the second suction device is simultaneously located above the loading platform. Contemporaneously with the movement of the arm, the supply conveyor has transported a second item to the loading platform. The first suction releases the item into an empty bucket while the second suction device simultaneously grips a second item from the loading platform. The arm is then moved back to its original position. The second suction device is now co-located directly above a bucket which contains a single item. As the first suction device grips an item, which has been conveyed to the landing site by the first conveyor, the second suction device simultaneously releases the second item into the bucket. The items are then loaded from the bucket into a box in a conventional manner. A drawback with this type of loader is that it does not use, nor is it easily adapted from, the single item loader mechanism. Moreover, problems are encountered if either suction device, when over the landing site, fails to pick up an item. This again, may result in a partially filled bucket leaving the loading station. A further drawback of this type of loader is its limitation to loading a maximum of two items per container and difficulty in operating the apparatus at high speeds.
Accordingly, it is desired to provide a method and apparatus for improved multi-item (i.e. two or more items) loading functionality and which may be operated at relatively high speeds. It is also desirable that such an apparatus or system be cost effectively adapted from existing single item loading mechanisms. Yet, the method and apparatus should attempt to minimize the likelihood of an item holder such as a bucket arriving at the container loading station carrying less than the full complement of items.